BaseTools/Source/C/Makefiles/header.makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=1764
Some compiler flags restrict the compiler from making
arbitrary decisions while handling undefined C/C++ behaviors.
Therefore they can be used to fix some issues caused by undefined behavior.
For example, for GCC, the following flags are available:
-fno-strict-overflow tells the compiler NOT to assume
that signed overflow does not occur.
-fno-delete-null-pointer-checks tells
the compiler NOT to assume that null pointer deference does not exist.
-fwrapv tells the compiler that signed overflow always wraps.
This patch is going to add these 3 build options to
BaseTool GCC build option.
Signed-off-by: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
---
BaseTools/Source/C/Makefiles/header.makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/BaseTools/Source/C/Makefiles/header.makefile b/BaseTools/Source/C/Makefiles/header.makefile
index 90fb3453ad..f1aed62769 100644
--- a/BaseTools/Source/C/Makefiles/header.makefile
+++ b/BaseTools/Source/C/Makefiles/header.makefile
@@ -68,11 +68,11 @@ BUILD_OPTFLAGS = -O2 $(EXTRA_OPTFLAGS)
ifeq ($(DARWIN),Darwin)
# assume clang or clang compatible flags on OS X
BUILD_CFLAGS = -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror -Wno-deprecated-declarations -Wno-self-assign -Wno-unused-result -nostdlib -g
else
-BUILD_CFLAGS = -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror -Wno-deprecated-declarations -Wno-stringop-truncation -Wno-restrict -Wno-unused-result -nostdlib -g
+BUILD_CFLAGS = -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror -Wno-deprecated-declarations -Wno-stringop-truncation -Wno-restrict -Wno-unused-result -nostdlib -g -fwrapv -fno-delete-null-pointer-checks -fno-strict-overflow
endif
BUILD_LFLAGS =
BUILD_CXXFLAGS = -Wno-unused-result
ifeq ($(HOST_ARCH), IA32)
--
2.20.1.windows.1
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Hi Bob, On 04/29/19 10:01, Bob Feng wrote: > BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=1764 > > Some compiler flags restrict the compiler from making > arbitrary decisions while handling undefined C/C++ behaviors. > Therefore they can be used to fix some issues caused by undefined behavior. > > For example, for GCC, the following flags are available: > -fno-strict-overflow tells the compiler NOT to assume > that signed overflow does not occur. > -fno-delete-null-pointer-checks tells > the compiler NOT to assume that null pointer deference does not exist. > -fwrapv tells the compiler that signed overflow always wraps. > > This patch is going to add these 3 build options to > BaseTool GCC build option. > > Signed-off-by: Bob Feng <bob.c.feng@intel.com> > Cc: Liming Gao <liming.gao@intel.com> > --- > BaseTools/Source/C/Makefiles/header.makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/BaseTools/Source/C/Makefiles/header.makefile b/BaseTools/Source/C/Makefiles/header.makefile > index 90fb3453ad..f1aed62769 100644 > --- a/BaseTools/Source/C/Makefiles/header.makefile > +++ b/BaseTools/Source/C/Makefiles/header.makefile > @@ -68,11 +68,11 @@ BUILD_OPTFLAGS = -O2 $(EXTRA_OPTFLAGS) > > ifeq ($(DARWIN),Darwin) > # assume clang or clang compatible flags on OS X > BUILD_CFLAGS = -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror -Wno-deprecated-declarations -Wno-self-assign -Wno-unused-result -nostdlib -g > else > -BUILD_CFLAGS = -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror -Wno-deprecated-declarations -Wno-stringop-truncation -Wno-restrict -Wno-unused-result -nostdlib -g > +BUILD_CFLAGS = -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror -Wno-deprecated-declarations -Wno-stringop-truncation -Wno-restrict -Wno-unused-result -nostdlib -g -fwrapv -fno-delete-null-pointer-checks -fno-strict-overflow (1) This line is hard to review. Please add a patch first that implements no functional changes, just splits this line into multiple <=80char lines, using the backslash. (2) When you add "-W" and "-f" options, please try to preserve the grouping. We already have two "-f" options, so the new ones should be adjacent to those. (3) My gcc-4.8 manual states, under "-fstrict-overflow": See also the -fwrapv option. Using -fwrapv means that integer signed overflow is fully defined: it wraps. When -fwrapv is used, there is no difference between -fstrict-overflow and -fno-strict-overflow for integers. With -fwrapv certain types of overflow are permitted. For example, if the compiler gets an overflow when doing arithmetic on constants, the overflowed value can still be used with -fwrapv, but not otherwise. The point is that, with gcc-4.8, "-fno-strict-overflow" is redundant, once we specify "-fwrapv" -- assuming we don't use floating point in the C-language utilities in BaseTools. Additionally, checking the latest published GCC docs on the web: https://gcc.gnu.org/onlinedocs/gcc-8.3.0/gcc/Option-Summary.html it looks like the "-f[no-]strict-overflow" option has been removed altogether. Therefore I believe we should drop "-fno-strict-overflow". Thanks, Laszlo > endif > BUILD_LFLAGS = > BUILD_CXXFLAGS = -Wno-unused-result > > ifeq ($(HOST_ARCH), IA32) > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#39798): https://edk2.groups.io/g/devel/message/39798 Mute This Topic: https://groups.io/mt/31381008/1787277 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [importer@patchew.org] -=-=-=-=-=-=-=-=-=-=-=-
Laszlo, thanks for your comments. I sent new patches for review. Thanks, Bob -----Original Message----- From: Laszlo Ersek [mailto:lersek@redhat.com] Sent: Tuesday, April 30, 2019 2:44 AM To: devel@edk2.groups.io; Feng, Bob C <bob.c.feng@intel.com> Cc: Gao, Liming <liming.gao@intel.com> Subject: Re: [edk2-devel] [Patch] BaseTools: Add GCC flags to Basetool build. Hi Bob, On 04/29/19 10:01, Bob Feng wrote: > BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=1764 > > Some compiler flags restrict the compiler from making arbitrary > decisions while handling undefined C/C++ behaviors. > Therefore they can be used to fix some issues caused by undefined behavior. > > For example, for GCC, the following flags are available: > -fno-strict-overflow tells the compiler NOT to assume that signed > overflow does not occur. > -fno-delete-null-pointer-checks tells > the compiler NOT to assume that null pointer deference does not exist. > -fwrapv tells the compiler that signed overflow always wraps. > > This patch is going to add these 3 build options to BaseTool GCC build > option. > > Signed-off-by: Bob Feng <bob.c.feng@intel.com> > Cc: Liming Gao <liming.gao@intel.com> > --- > BaseTools/Source/C/Makefiles/header.makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/BaseTools/Source/C/Makefiles/header.makefile > b/BaseTools/Source/C/Makefiles/header.makefile > index 90fb3453ad..f1aed62769 100644 > --- a/BaseTools/Source/C/Makefiles/header.makefile > +++ b/BaseTools/Source/C/Makefiles/header.makefile > @@ -68,11 +68,11 @@ BUILD_OPTFLAGS = -O2 $(EXTRA_OPTFLAGS) > > ifeq ($(DARWIN),Darwin) > # assume clang or clang compatible flags on OS X BUILD_CFLAGS = -MD > -fshort-wchar -fno-strict-aliasing -Wall -Werror > -Wno-deprecated-declarations -Wno-self-assign -Wno-unused-result > -nostdlib -g else -BUILD_CFLAGS = -MD -fshort-wchar > -fno-strict-aliasing -Wall -Werror -Wno-deprecated-declarations > -Wno-stringop-truncation -Wno-restrict -Wno-unused-result -nostdlib -g > +BUILD_CFLAGS = -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror > +-Wno-deprecated-declarations -Wno-stringop-truncation -Wno-restrict > +-Wno-unused-result -nostdlib -g -fwrapv > +-fno-delete-null-pointer-checks -fno-strict-overflow (1) This line is hard to review. Please add a patch first that implements no functional changes, just splits this line into multiple <=80char lines, using the backslash. (2) When you add "-W" and "-f" options, please try to preserve the grouping. We already have two "-f" options, so the new ones should be adjacent to those. (3) My gcc-4.8 manual states, under "-fstrict-overflow": See also the -fwrapv option. Using -fwrapv means that integer signed overflow is fully defined: it wraps. When -fwrapv is used, there is no difference between -fstrict-overflow and -fno-strict-overflow for integers. With -fwrapv certain types of overflow are permitted. For example, if the compiler gets an overflow when doing arithmetic on constants, the overflowed value can still be used with -fwrapv, but not otherwise. The point is that, with gcc-4.8, "-fno-strict-overflow" is redundant, once we specify "-fwrapv" -- assuming we don't use floating point in the C-language utilities in BaseTools. Additionally, checking the latest published GCC docs on the web: https://gcc.gnu.org/onlinedocs/gcc-8.3.0/gcc/Option-Summary.html it looks like the "-f[no-]strict-overflow" option has been removed altogether. Therefore I believe we should drop "-fno-strict-overflow". Thanks, Laszlo > endif > BUILD_LFLAGS = > BUILD_CXXFLAGS = -Wno-unused-result > > ifeq ($(HOST_ARCH), IA32) > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#39844): https://edk2.groups.io/g/devel/message/39844 Mute This Topic: https://groups.io/mt/31381008/1787277 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [importer@patchew.org] -=-=-=-=-=-=-=-=-=-=-=-
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